A Distributed Antenna System (DAS) typically includes one or more master units that are communicatively coupled with a plurality of remote antenna units, where each remote antenna unit can be coupled directly to one or more of the master units or indirectly via one or more other remote antenna units and/or via one or more intermediary or expansion units. A DAS is typically used to improve the coverage provided by one or more base stations that are coupled to the master units. These base stations can be coupled to the master units via one or more cables or via a wireless connection, for example, using one or more donor antennas. The wireless service provided by the base stations can included commercial cellular service and/or private or public safety wireless communications.
When planning for coverage of tunnels, buildings, train stations, airports, stadiums and similar facilities that present public safety challenges and concerns, maintaining DAS communications coverage in the facility during emergency events is an important consideration. For that reason, DAS operators may be required to provide remote antenna units with connections to their master units using two redundant cables (for example, optical fibers) laid through two different, spatial separated, independent areas. For example, one way to address this need is through optical link redundancy (OLR), which provides a fully redundant link between the master and remote antenna units in addition to the main optical fiber link. OLR provides for two completely redundant optical links, not only redundant optical fibers but also redundant optical transceivers at both the master unit and remote antenna unit sites.
However, for public safety operators, this redundant and expensive equipment remains dormant most of the time, except for when emergency situations require its operation.